AEMET said the red alert would be in effect from 10:00 am (0800 GMT) on Friday in Mediterranean coastal regions of the province of Alicante, as well as in the neighbouring region of Murcia.

"Extraordinary danger. Flooding and flash floods may occur. Follow the advice of civil protection," the agency wrote on X.

Rainfall totals could exceed 140 millimetres (five and a half inches) in 12 hours, especially in Valencia, the weather office said.

Widespread flooding in another part of Valencia in October 2024 killed more than 200 people, Spain's worst such disaster in decades.

The catastrophe sparked public fury over warning systems and the emergency response. Residents continue to protest, accusing officials of having failed to provide timely alerts.

Heavy rains lashed the region again last month, forcing the closure of schools and universities, disrupting rail and road travel and causing localised flooding.

Because a hotter atmosphere holds more water that evaporates from a rapidly warming Mediterranean Sea, climate change increases the risk and intensity of flooding from extreme rainfall in the region.